What happens if a cheque is found to be fraudulent well after the end of the 6th working day after I have paid in my cheque?
All customers are protected provided they are not a knowing party to a fraud and each case would be looked at on an individual basis. If there is a dispute, you can seek redress through the bank or building society's own formal complaints procedure, which under BCOBS (the Banking Conduct of Business Sourcebook) all banks and building societies are obliged to tell theri customers.
Failing satisfactory resolution, you can refer your complaint to an independent assessment by the Financial Ombudsman Service.